With the increasing miniaturization of semiconductor elements contained in a semiconductor integrated circuit device such as an LSI (Large Scale Integrated Circuit), variations in characteristics of a semiconductor element such as a threshold voltage of a field effect transistor including a MISFET (Metal Insulator Semiconductor Field Effect Transistor) have been increasing. As a technique for compensating for the variations in characteristics of a semiconductor element, a technique of applying a substrate bias to a semiconductor substrate has been conventionally known. By applying a substrate bias to the semiconductor substrate having MISFETs formed thereon, the threshold voltage of the MISFETs can be controlled, and it is possible to compensate for the variations in the threshold voltage.
Japanese Patent Application Laid-Open Publication No. 2001-156261 (Patent Document 1) has disclosed a technique in which a speed monitor circuit and a substrate bias control circuit are provided for a main circuit composed of MISFETs and a substrate bias is generated so that a speed signal set in accordance with an operating speed and a speed detection signal corresponding to the operating speed coincide with each other.
Japanese Patent Application Laid-Open Publication No. 8-274620 (Patent Document 2) has disclosed a technique in which a substrate bias of an oscillator circuit of a substrate-bias dependent type is used in common with a substrate bias of a main circuit and the threshold voltage of the MISFETs constituting the main circuit is controlled in accordance with an operation mode.
Japanese Patent Application Laid-Open Publication No. 2009-44220 (Patent Document 3) has disclosed a technique in which the threshold voltage is controlled by applying a substrate bias to a back gate of MISFET, thereby compensating for the variations in threshold voltage of the MISFETs.
Japanese Patent Application Laid-Open Publication No. 2009-64860 (Patent Document 4) has disclosed a technique in which MISFETs are formed on a main surface of an SOI (Silicon On Insulator) substrate and the threshold voltage is controlled by applying a substrate bias to a support substrate below the MISFETs.